meet the AR interface requirements.

now supports mapped primary key when _id is part of source with an
alias.

- allows to have dynamic definition of attributes depended on the
  instance
- there was no real need for it to be static. Places that used it static
  have been refactored.

fixes #1318

- make use of traits
- short array
- better implementation of query findByPk

http://www.yiiframework.com/forum/index.php/topic/48359-inserting-nulls/page__view__findpost__p__226019

closes #1084

- introduced RecordSchema class for schema definition

Appended newlines to every PHP document that did not have a newline as the last character in the file.

relations are not working yet